1. Technical Field
The present invention relates to a liquid ejecting apparatus such as an ink jet type recording apparatus, and a method of controlling the liquid ejecting apparatus, and particularly to a liquid ejecting apparatus which drives a piezoelectric element by applying a drive potential to the piezoelectric element and thus causing liquid to be ejected from a nozzle, and a method of controlling the liquid ejecting apparatus.
2. Related Art
A liquid ejecting apparatus includes liquid ejecting heads, and is an apparatus which ejects (discharges) various liquids from the liquid ejecting heads. As the liquid ejecting apparatus, there is an image recording apparatus such as an ink jet type printer or an ink jet type plotter, but recently, for utilizing a feature that a very small amount of liquid can be landed exactly at a predetermined position, the liquid ejecting apparatus has also been applied to various manufacturing apparatuses. For example, the liquid ejecting apparatus is applied to a display manufacturing apparatus which manufactures a color filter of a liquid crystal display or the like, an electrode forming apparatus which forms an electrode of an organic EL (electro luminescence) display, an FED (field emission display) or the like, and a chip manufacturing apparatus which manufactures a biochip (biochemical element). Subsequently, a recording head for the image recording apparatus ejects ink of liquid form, and a color material ejecting head for a display manufacturing apparatus ejects liquids of each of color materials of R (Red), G (Green), and B (Blue). In addition, an electrode material ejecting head for an electrode forming apparatus ejects liquid electrode material, and a bio organic material ejecting head for a chip manufacturing apparatus ejects liquid of bio-organic material.
A recording head mounted on a printer is configured in such a manner that ink from an ink supply source such as an ink cartridge flows into a pressure chamber, a drive potential (drive voltage) is applied to a piezoelectric element thereby operating the piezoelectric element and then a pressure variation occurs in the ink in the pressure chamber, and by using the pressure variation, the ink in the pressure chamber is ejected from a nozzle as ink droplets. In addition, with regard to pressure chambers (hereinafter, appropriately, referred to as end portion pressure chambers) which are positioned at both ends in a linear alignment direction among a plurality of linearly aligned pressure chambers, on one side of the end portion pressure chamber, other pressure chambers are adjacent to each other with partition walls therebetween, while on the other side of the end portion pressure chamber, a wall with a high rigidity and thicker than the partition wall between the pressure chambers is provided. Since it is difficult for this wall to be deformed even by the pressure variation when compared with the partition wall between the pressure chambers, pressure loss at the time of ejection of the liquid in the end portion pressure chamber is small when compared with that of a pressure chamber (pressure chamber which is positioned inside in the linear alignment direction with respect to the end portion pressure chambers) other than the end portion pressure chambers. As a result, a difference of pressure loss occurs between pressure chambers which are positioned on the inside and pressure chambers which are positioned at both ends, among the plurality of linearly aligned pressure chambers, and thereby differences in an amount of liquid ejected from the nozzle and in flying speed (ejection characteristics) occur.
With regard to this point, a recording head in which a dummy pressure chamber that is adjacent to the end portion pressure chamber and does not perform the ejection of liquid is formed, is also proposed (for example, refer to JP-A-2004-262242). That is, when providing the dummy pressure chamber so as to be adjacent to the end portion pressure chamber, partition walls with the same strength can be provided on both sides of the end portion pressure chamber, and thereby conditions on structures of the end portion pressure chambers can be made uniform to the same degree as those of other pressure chambers which are positioned on the inside. Furthermore, the ink of the same type as the ink filled into the other pressure chambers is filled into the dummy pressure chamber. As a result, it is possible to make uniform the pressure loss at the end portion pressure chamber and the pressure chambers on the inside, when the liquid is ejected.
However, recently, for this type of recording head, in order to respond to requirements for image quality improvement of the recorded image or miniaturization of the recording head, an increase in density of nozzles has progressed further. As a result, pressure chambers in communication with each nozzle has also been formed with high density, and a partition wall which partitions pressure chambers adjacent to each other has tended to become thinner. In addition, based on an advantage that a shape of a small pressure chamber can be formed with a high dimensional accuracy, a single crystal silicon substrate can be used as a material for forming the pressure chamber. The rigidity of the partition wall in a case where the pressure chamber is formed by a single crystal silicon substrate is weak, when compared with that of a metal such as stainless steel. Due to circumstances such as these, there have been lots of cases where it has been difficult to make uniform ejection characteristics of the end portion pressure chambers and pressure chambers on the inside at the time of the ejection of the liquid, only by simply providing a dummy pressure chamber.
In addition, such a problem exists not only in an ink jet type recording apparatus on which a recording head that ejects ink is mounted, but also in other liquid ejecting apparatuses which eject liquid from a nozzle by generating a pressure variation in the liquid in a pressure chamber.